WASHINGTON – President Donald Trump is privately rejecting the growing consensus among Republican leaders that they may lose the House and possibly the Senate in November, leaving party officials and the president’s advisers nervous that he does not grasp the gravity of the threat they face in the midterm elections.

Congressional and party leaders and even some Trump aides are concerned that the president’s boundless self-assurance about politics will cause him to ignore or undermine their midterm strategy. In battleground states like Arizona, Florida and Nevada, Trump’s proclivity to be a loose cannon could endanger the Republican incumbents and challengers who are already facing ferocious Democratic headwinds.

Republicans in Washington and Trump aides have largely given up assuming the president will ever stick to a teleprompter, but they have joined together to impress upon him just how bruising this November could be for Republicans — and how high the stakes are for Trump personally, given that a Democratic-controlled Congress could pursue aggressive investigations and even impeachment.

Over dinner with the president and other Republican congressional leaders this month, Sen. Mitch McConnell, R-Ky., the majority leader, phrased his advice for the president in the form of a reminder: Trump should never forget his central role in the 2018 campaign, McConnell said, explaining that Republicans’ prospects are linked to what he says and does and underscoring that their one-seat advantage in the Senate is in jeopardy.

If McConnell’s warning was not clear enough, Marc Short, the White House’s legislative liaison, used the dinner to offer an even starker assessment. The GOP’s House majority is all but doomed, he said.

But Trump was not moved. “That’s not going to happen,” he said at different points during the evening, according to multiple officials briefed on the conversation.

The disconnect between the president — a political novice whose confidence in his instincts was grandly rewarded in 2016 — and more traditional party leaders demonstrates the depth of the Republicans’ challenges in what is likely to be a punishing campaign year.

Trump is as impulsive as ever, fixated on personal loyalty, cultivating a winner’s image and privately prodding GOP candidates to demonstrate their affection for him — while complaining bitterly when he campaigns for those who lose. His preoccupation with the ongoing Russia investigation adds to the unpredictability, spurring Trump to fume aloud in ways that divide the GOP and raising the prospect of legal confrontations amid the campaign.

According to advisers, the president plans to hold a fundraiser a week in the months to come and hopes to schedule regular rallies with candidates starting this summer. But there is not yet any coordinated effort about where to deploy Trump, and there are divisions within his ever-fractious circle of advisers about how to approach the elections.

Congressional leaders have left little doubt in private that they see Trump as a political millstone for many of the party’s candidates. In recent weeks, McConnell has confided to associates that Republicans may lose the Senate because of the anti-Trump energy on the left.

Trump, for his part, has complained to associates about having been deployed to campaign for relatively weak Republicans like Roy Moore, who lost the 2017 Senate race in Alabama, and Rick Saccone, who lost the special House election in Pennsylvania in March.

He has taken the losses personally, particularly in Alabama, because the vacancy there was a result of his decision to make Jeff Sessions attorney general, an appointment he has since regretted. Trump has subsequently blamed others in the party for thrusting him into episodes of humiliating defeat.

The scars from those races have made Trump reluctant to weigh in on the race that Senate Republicans most want his imprint on right now: the contest to replace Sen. Thad Cochran, R-Miss., who resigned this month.

Despite the lingering disputes with congressional Republicans, White House officials say Trump is eager to return to the campaign trail.

Although some Republicans in competitive states may not want to appear with Trump — Gov. Scott Walker of Wisconsin, for example, has told associates he is unlikely to campaign with the president — there is no lack of lawmakers eager for his help.

Rep. Lee Zeldin, R-N.Y., said he would welcome Trump on the trail anytime.

“I would expect the president and vice president to be in congressional districts all across the country,” Zeldin said. “I’ve gotten nothing but positive feedback on the desire of the president’s team to be as helpful as possible.”